Sports' Secret Weapon: Sleep

The search for performance enhancement leads some athletes to turn some pretty dark corners. It's a shame, and not just because doping is dangerous, unethical, and frequently illegal. It's also a shame because athletes at all levels of play have access to a powerful tool to improve their performance, one that won't break any laws or put anyone's health at risk.

What's this wonder drug? Sleep.

There's been a welcome uptick in the attention paid by the media and athletic professionals to the benefits of sleep for competitive athletes and to the research that shows just how sleep can improve physical performance in sport. This season, the New York Jets brought sleep specialists into the locker room, signaling their intention to use sleep as part of their training strategy. At the other end of the spectrum, I was disappointed to read that Manchester United is addressing its players sleep issues by issuing sleeping pills. This strategy -- and the coach's seemingly-cavalier attitude toward medicating players for sleep -- is not what I recommend when I suggest that athletes and coaches pay more attention to sleep.

In recent years, Stanford University's Center for Sleep Sciences and Medicine has been at the leading edge of examining the sleep-sport performance connection. Researchers there have conducted studies with several groups of Stanford student-athletes, examining the effects of extended sleep on athletic performance. Here's a sampling of their results, which show improvements across a variety of sports:

Swimming: Five members of the Stanford men's and women's swimming teams increased their sleep goal to 10 hours per night for a period of 6-7 weeks. This led to improvements in speed, reaction time, turn times and kick strokes. Swimmers shaved an average of .51 seconds off a 15-meter sprint, they left the blocks .15 seconds faster, shaved .10 seconds off their average turn time, and added an average of five kicks to their stroke frequency. Out of the water, swimmers reported reductions in their levels of daytime sleepiness, improvements to their mood, more energy and less fatigue.

Tennis: Researchers asked five members of the women's tennis team to increase their sleep goal to 10 hours per night for 5-6 weeks. Players improved their sprint times, dropping from an average of 19.12 to 17.56 seconds. They also increased their serve accuracy, going from an average of 12.6 valid serves to 15.61.

Football: Seven players on the Stanford football team spent 7-8 weeks attempting to sleep for 10 hours per night. Their extended sleep resulted in improvements to their 20-yard shuttle -- average time decreased to 4.61 seconds from 4.71 -- and to their 40-yard dash, which dropped to an average of 4.89 from 4.99 seconds. (Both the shuttle and the dash are among the drills conducted at the NFL Scouting Combine.) Players also reported improvements to their daytime energy levels and mood and reduced daytime fatigue.

Basketball: For 5-7 weeks, 11 members of the university's basketball team extended their nightly sleep to 10 hours. As a result, shooting accuracy among the players improved significantly: Free-throw shooting improved 9 percent, and three-point shooting 9.2 percent.

Sensing a pattern? Extending sleep times translated into significant improvements to critical game-day skills. Worth noting: Not all athletes across these studies actually slept for 10 hours per night, but attempting to sleep for 10 hours per night got them additional sleep compared to their regular routine. According to researchers, many of these athletes came to their sleep-sport studies already sleep deprived.

And that gets to the flipside of the advantages that additional sleep can give to athletes. Sleep deficiency can inhibit performance. Research shows lack of sleep can also affect the longevity of players' careers. Two recent studies investigated the relationship between sleep and career duration and stability among NFL players and MLB players. The NFL study looked at 55 players from across the league. Those who reported higher levels of daytime sleepiness were less likely to remain with the team that drafted them than those players who reported lower levels of daytime tiredness. And MLB players who reported higher levels of daytime tiredness had attrition rates far higher than league averages.

There's also evidence that sleep can increase the risk of injury among athletes. In this study of teenage student-athletes, those who slept at least eight hours per night were 68 percent less likely to injure themselves playing sports than those who slept less than eight hours nightly. Researchers examined the sleep patterns and sports-related injuries of 112 male and female athletes from grades 7-12. They discovered that sleep and age were the most significant factors in assessing injury risk. (In addition to being more injury-prone when short on sleep, students were also more likely to injure themselves as they moved to higher grade levels.)

So what's behind the performance boost from sleep?

The cognitive benefits of sleep translate onto the field. Memory, learning, reaction time and focus: Sleep is critical to the brain's ability to perform these mental tasks efficiently and well. The brain uses sleep to consolidate memory into longer-term knowledge, clearing the area of the brain used for short-term memory in preparation to absorb new information. During sleep, the brain also works to prioritize the information it thinks will be important in the future. Sleep deprivation has well-studied negative effects on reaction times -- and even a single night of sleep deprivation can slow quick response times.

Sleep promotes muscle recovery. Sleep is a critical time for cell regeneration and repair in the body. During non-REM stages of sleep, cell division and regeneration actually becomes more active than during waking hours. Insufficient sleep, on the other hand, can hinder muscle recovery.

Sleep is a stress-reducer. Sleep and stress have a tangled relationship -- and both are dangerous to healthy immune function when we don't get enough (sleep), or have too much (stress). Stress can interfere with sleep -- this study ranked worry as the most common cause of sleeplessness among adults 34-79. But lack of sleep can also affect mood and make us more susceptible to stress and anxiety.

Is sleep the next big thing in sports? I'd say it's more than earned its shot in the big show.